State of the Art
The invention is based on a brake actuator, particularly for a rail vehicle brake.
Essentially, three braking systems are currently used in the rail vehicle field: pneumatic or electro-pneumatic braking systems, hydraulic or electro-hydraulic braking systems as well as mechanical or electro-mechanical braking systems. The braking system may be constructed as an active or passive braking system, depending on whether the force of the brake actuator is to be applied for an engaging (active braking system) or a releasing of the brake (passive braking system). In the event of operating disturbances, in the case of pneumatic systems, an energy accumulation takes place in compressed-air reservoirs; in the case of hydraulic systems, an energy accumulation takes place in hydraulic reservoirs; and in the case of mechanical systems, an energy accumulation takes place in the form of accumulator-type springs.
From US Patent Document U.S. Pat. No. 4,546,298, an electromechanical rail vehicle brake is known which has a service brake unit as well as an energy storage brake unit with an energy accumulator. The service brake unit contains a braking force generator for the application and/or release of the brake, for example, in the form of an electric-motor drive. The energy storage brake unit comprises at least one energy accumulator for storing and supplying energy for the application of the brake as an operational emergency brake in the event of a failure of the service brake unit, and/or as a parking brake. The energy storage brake is generally constructed as a spring-loaded brake. An energy converter carries out a conversion of the energy supplied by the braking force generator and/or by the energy accumulator to a brake application movement and comprises, for example, a brake spindle driven by the electric-motor drive.
Since the entire braking force or the entire releasing force is applied by the electric-motor drive as the braking force generator, the drive has to be designed for a high output torque. The braking force generator is therefore relatively large and consequently also relatively heavy and expensive.
U.S. Patent Document U.S. Pat. No. 4,784,244 describes an electrically operable brake actuator with an accumulator-type spring which, in the event of a service braking, builds up a fraction of the braking force.